1. Technical Field
The present invention relates to a plasma treatment apparatus and a plasma treatment method.
2. Related Art
Conventionally, there is known a plasma treatment apparatus which performs a plasma treatment on a surface of a work (See, for example, JP-A-6-244175 and JP-A-7-211769). FIG. 3 is a vertical sectional view which schematically shows a configuration of a conventional plasma treatment apparatus.
Specifically, the plasma treatment apparatus 100 shown in FIG. 3 includes a stage (first electrode) 120 provided with an electrostatic chuck (electrostatic absorption unit) 125 for holding a wafer (work) 110, an electrode 130 for generating plasma (second electrode) arranged to face the first electrode 120 via the wafer 110, a gas supply unit 140 for supplying a gas between the wafer 110 and the second electrode 130, a high frequency power source 150 for applying a high frequency voltage across the first electrode 120 and the second electrode 130, and a chamber 160 in which the wafer 110, the first electrode 120 and the second electrode 130 are housed (See, for example, JP-A-7-211769).
In such a plasma treatment apparatus 100, when a high frequency voltage is applied across the first electrode 120 and the second electrode 130 while supplying a particular gas between the wafer 110 and the second electrode 130, the gas is converted into a plasma. As a result, the plasma treatment is performed on the wafer 110 due to the action of an activate atom or activate molecule contained in the thus generated plasma.
However, in the plasma treatment apparatus 100, in the case where a space is formed between the wafer 110 mounted on the first electrode 120 and the first electrode 120, the following defect occurs. Specifically, if a distance of the formed space between two objects (the wafer 110 and the first electrode 120) is too small, discharge readily occurs between the two objects.
Therefore, in the case where only a small warpage is present in the wafer 110, a space is formed between the wafer 110 and the first electrode 120 due to the warpage of the wafer 110. As a result, discharge readily occurs between the wafer 110 and the first electrode 120 due to the existence of the space. Especially, in the case of a wafer 110 made of a metallic material and having too thin thickness, warpage is easily to occur, the above mentioned tendency becomes noticeable.
When discharge occurs between the wafer 110 and the first electrode 120, there is a case that a portion of the wafer 110 at which the discharge occurs is degenerated or deteriorated. In the case where the degenerated or deteriorated portion of the wafer 110 is used for producing products or parts, the products or parts become defective goods.